Performance assessment of Molten Carbonate Fuel Cell–Humid Air Turbine hybrid systems

Abstract

One of the most promising technologies for stationary power applications is the Molten Carbonate Fuel Cell (MCFC). This is due to its high efficiency, low emissions and the medium–high operating temperature. This high temperature allows for hybridization with other power generation technologies where the bottoming cycle recovers part of the heat in the fuel cell exhaust stream, hence resulting in highly efficient hybrid systems. The current MCFC hybrid system designs use microturbines as bottoming cycle.This paper presents the integration of a MCFC with a bottoming Humid Air Turbine (HAT) instead of the conventional microturbine. The HAT cycle, even if still under development, provides a relatively simple and inexpensive solution to increase the power output of the microturbine. An indirect integration between the MCFC and the HAT cycle is chosen aiming to simplify the layout and operation of the new system and considering that the necessary modifications to be performed in the microturbine are relatively simple (and therefore the additional equipment is expected to be relatively economical).The results presented in this paper show the potential of this MCFC–HAT combination with an increase of the net power output of 6 percentage points and an efficiency increase of 3 percentage points from the high efficiency conventional hybrid system (MCFC–MGT). An economic analysis as function of the MCFC investment cost is presented showing a break-even-cost of 2092 €/kW improving the estimated for the MCFC–MGT.